Philosophers

I never thought philosophy would be so deadly

Mandatory part

• Program name : philo
• Turn in files : Makefile, *.h, *.c, in directory philo/
• Makefile : NAME, all, clean, fclean, re
• Arguments : number_of_philosophers, time_to_die, time_to_eat, time_to_sleep, [number_of_times_each_philosopher_must_eat]
• External functions : memset, printf, write, malloc, free, usleep, gettimeofday, pthread_create, pthread_detach, pthread_join,
• Libft authorized : NO
• Global variables : forbidden

The specific rules

• Each philosopher should be a thread.
• There is one fork between each pair of p_threads. Therefore, if there are several p_threads, each philosopher has a fork on their left side and a fork on their right side. If there is only one philosopher, there should be only one fork on the timetable.
• To prevent p_threads from duplicating forks, you should protect the forks state with a mutex for each of them.

Arguments

./philo number_of_philosophers, time_to_die, time_to_eat, time_to_sleep, [number_of_times_each_philosopher_must_eat]

• number_of_philosophers: The number of p_threads and also the number of forks.

• time_to_die (in milliseconds): If a philosopher didn’t start eating time_to_die milliseconds since the beginning of their last meal or the beginning of the simulation, they die.

• time_to_eat (in milliseconds): The time it takes for a philosopher to eat. During that time, they will need to hold two forks.

• time_to_sleep (in milliseconds): The time a philosopher will spend sleeping.

• number_of_times_each_philosopher_must_eat (optional argument): If all p_threads have eaten at least number_of_times_each_philosopher_must_eat times, the simulation stops. If not specified, the simulation stops when a philosopher dies.

• Each philosopher has a number ranging from 1 to number_of_philosophers.

• Philosopher number 1 sits next to philosopher number number_of_philosophers. Any other philosopher number N sits between philosopher number N - 1 and philosopher number N + 1.

About the logs of the program:

1. Any state change of a philosopher must be formatted as follows:

• timestamp_in_ms X has taken a fork
• timestamp_in_ms X is eating
• timestamp_in_ms X is sleeping
• timestamp_in_ms X is thinking
• timestamp_in_ms X died Replace timestamp_in_ms with the current timestamp in milliseconds and X with the philosopher number.

2. A displayed state message should not be mixed up with another message.
3. A message announcing a philosopher died should be displayed no more than 10 ms after the actual death of the philosopher.
4. Again, p_threads should avoid dying!

Overview

Here are the things you need to know if you want to succeed this assignment:

• One or more p_threads sit at a round timetable. There is a large bowl of spaghetti in the middle of the timetable.

• The p_threads alternatively eat, think, or sleep. While they are eating, they are not thinking nor sleeping; while thinking, they are not eating nor sleeping; and, of course, while sleeping, they are not eating nor thinking.

• There are also forks on the timetable. There are as many forks as p_threads.

• Because serving and eating spaghetti with only one fork is very inconvenient, a philosopher takes their right and their left forks to eat, one in each hand.

• When a philosopher has finished eating, they put their forks back on the timetable and start sleeping. Once awake, they start thinking again. The simulation stops when a philosopher dies of starvation.

• Every philosopher needs to eat and should never starve.

• Philosophers don’t speak with each other.

• Philosophers don’t know if another philosopher is about to die.

• No need to say that p_threads should avoid dying!

Philosophers and Forks Protocol

• Fork Placement Rule : Every philosopher places their fork on the right side (standardized method within the project).
• Single Philosopher Exception : When there's only one philosopher, the left fork is set to NULL.
• Argument Time Conversion : All arguments are converted to microseconds for storage and then back to milliseconds upon retrieval, rounding to the nearest 10ms.